Question

Which of the following are features of the alveoli that adapt them to gas exchange?
I. )High surface area
II )thin walls
III) dry surfaces

Answer 1

Answer: II )thin walls

Explanation:

• Alveoli is present in the lungs and are the actual site where the exchange of gases takes place.
• To exchange gases more efficiently the walls of the alveoli are thin which provide a larger surface area to make the exchange of gases properly.
• Hence, option II is the most appropriate.

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Answer 2

Adaptations of the alveoli:

Thin walls - alveolar walls are one cell thick providing gases with a short diffusion distance. Moist walls - gases dissolve in the moisture helping them to pass across the gas exchange surface. Permeable walls - allow gases to pass through.

Features of Gas Exchange Surfaces

1. Large surface area to allow faster diffusion of gases across the surface.
2. Thin walls to ensure diffusion distances remain short.
3. Good ventilation with air so that diffusion gradients can be maintained.
4. Good blood supply to maintain a high concentration gradient so diffusion occurs faster.

Hence,

Option (II) thin walls are correct.

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